V. Ryjov

Fast Beam Conditions Monitor BCM1F for the CMS Experiment

The CMS Beam Conditions and Radiation Monitoring System, BRM, will support beam tuning, protect the CMS detector from adverse beam conditions, and measure the accumulated dose close to or inside all sub-detectors. It is composed of different sub-systems measuring either the particle flux near the beam pipe with time resolution between nano- and microseconds or the integrated dose over longer time intervals. This paper presents the Fast Beam Conditions Monitor, BCM1F, which is designed for fast flux monitoring measuring both beam halo and collision products. BCM1F is located inside the CMS pixel detector volume close to the beam-pipe. It uses sCVD diamond sensors and radiation hard front-end electronics, along with an analog optical readout of the signals. The commissioning of the system and its successful operation during the first beams of the LHC are described.

The NA62 Liquid Krypton calorimeter readout module

The NA62 experiment [1] at CERN SPS (Super Proton Synchrotron) accelerator will be focused on precision tests of the Standard Model via studies of ultra-rare decays of charged kaons. The high resolution Liquid Krypton (LKr) calorimeter of the former NA48 experiment [2], together with other detectors, will provide a photon-veto with hermetic coverage from zero out to large angles from the decay region. The old backend electronics [3] does not satisfy the NA62 specifications and the study of a new readout system began in 2008. This paper presents the Calorimeter REAdout Module (CREAM), an upgrade project for the backend part of the LKr data acquisition chain [3]. The CREAMs will provide 40 MHz sampling of 13248 calorimeter channels, data buffering during the SPS spill, zero suppression, and programmable trigger sums for the experiment trigger processor.

Fast beam conditions monitor (BCM1F) for CMS

The CMS Beam Conditions and Radiation Monitoring System (BRM) [1] is composed of different subsystems that perform monitoring of, as well as providing the CMS detector protection from, adverse beam conditions inside and around the CMS experiment. This paper presents the Fast Beam Conditions Monitoring subsystem (BCM1F), which is designed for fast flux monitoring based on bunch by bunch measurements of both beam halo and collision product contributions from the LHC beam. The BCM1F is located inside the CMS pixel detector volume close to the beam-pipe and provides real-time information. The detector uses sCVD (single-crystal Chemical Vapor Deposition) diamond sensors and radiation hard front-end electronics, along with an analog optical readout of the signals.

Electron identification with a prototype of the Transition Radiation Tracker for the ATLAS experiment: ATLAS TRT collaboration

Abstract A prototype of the Transition Radiation Tracker (TRT) for the ATLAS detector at the LHC has been built and tested. The TRT is an array of straw tubes which integrate tracking and electron identification by transition radiation into one device. Results of experimental measurements and of comparisons with Monte-Carlo simulations are presented for the electron identification performance as a function of various detector parameters. Under optimal operating conditions, a rejection against pions of a factor 100 was achieved with 90% electron efficiency.

Recent aging studies for the ATLAS transition radiation tracker

The transition radiation tracker (TRT) is one of the three subsystems of the inner detector of the ATLAS experiment. It is designed to operate for 10 yr at the LHC, with integrated charges of /spl sim/10 C/cm of wire and radiation doses of about 10 Mrad and 2/spl times/10/sup 14/ neutrons/cm/sup 2/. These doses translate into unprecedented ionization currents and integrated charges for a large-scale gaseous detector. This paper describes studies leading to the adoption of a new ionization gas regime for the ATLAS TRT. In this new regime, the primary gas mixture is 70%Xe-27%CO/sub 2/-3%O/sub 2/. It is planned to occasionally flush and operate the TRT detector with an Ar-based ternary mixture, containing a small percentage of CF/sub 4/, to remove, if needed, silicon pollution from the anode wires. This procedure has been validated in realistic conditions and would require a few days of dedicated operation. This paper covers both performance and aging studies with the new TRT gas mixture.

The performance of the Beam Conditions and Radiation Monitoring System of CMS

The Beam Conditions and Radiation Monitoring System (BRM), is installed in CMS to protect the CMS detector from high beam losses and to provide feedback to the LHC and CMS on the beam conditions. The primary detector subsystems are based on either single crystal diamond sensors (BCM1F) for particle counting with nanosecond resolution or on polycrystalline diamonds (BCM2; BCM1L) for integrated signal current measurements. Beam scintillation counters (BSC) are also used during low luminosity running. The detectors have radiation hard front-end electronics and are read out independently of the CMS central data acquisition and are online whenever there is beam in the LHC machine. The various sub-systems exploit different time resolutions and position locations to be able to monitor the beam induced backgrounds and the flux of particles produced during collisions. This paper describes the CMS BRM system and the complementary aspects of the installed BRM sub-detectors to measure both single particle count rates and signal currents originating from beam backgrounds and collision products in CMS.

The NA62 liquid Krypton calorimeter's new readout system

The NA62 experiment [1] at CERN SPS (Super Proton Synchrotron) accelerator aims at studying Kaon decays with high precision. The high resolution Liquid Krypton (LKr) calorimeter, built for the NA48 [2] experiment, is a crucial part of the experiment photon-veto system; to cope with the new requirements, the back-end electronics of the LKr had to be completely renewed.Due to the huge number of the calorimeter readout channels ( ~ 14 K) and the maintenance requirement over 10 years of the experiment lifetime, the decision to sub-contract the development and production to industry was taken in 2011. This paper presents the primary test results of the Calorimeter REAdout Module (CREAM) [3] prototype delivered by the manufacturer in March 2013. All essential features, analog performance, data processing and readout, are covered.

Progress in the development of the DTMROC time measurement chip for the ATLAS Transition Radiation Tracker (TRT)

A 16-channel digital time-measurement readout chip (DTMROC) has been fabricated in the TEMIC/DMILL BI-CMOS radiation-hard process for the Large Hadron Collider (LHC) Transition Radiation Tracker (ATLAS/TRT) at CERN. The chip receives discriminated straw-drift-tube signals from bipolar amplifier-shaper-discriminator chips (ASDBLR), measures the arrival time in 3.125 ns increments (/spl plusmn/1 ns), and stores the data in a pipeline for 3.3 /spl mu/s. A trigger signal (L1A) causes the data to be tagged with a time stamp and stored for readout. Up to 13 events may be stored in an on-chip buffer while data is being clocked out in a 40 MHz serial stream. The chip has been designed to function after exposure to 1/spl times/10/sup 14/ protons/cm/sup 2/ and 1 Mrad total dose. System beam-tests have demonstrated measurement of track positions with a resolution of 165 /spl mu/m and 85% efficiency at rates up to 18 MHz.

Acceptance tests and criteria of the ATLAS transition radiation tracker

The Transition Radiation Tracker (TRT) sits at the outermost part of the ATLAS Inner Detector, encasing the Pixel Detector and the Semi-Conductor Tracker (SCT). The TRT combines charged particle track reconstruction with electron identification capability. This is achieved by layers of xenon-filled straw tubes with periodic radiator foils or fibers providing TR photon emission. The design and choice of materials have been optimized to cope with the harsh operating conditions at the LHC, which are expected to lead to an accumulated radiation dose of 10 Mrad and a neutron fluence of up to 2middot1014 n/cm2 after ten years of operation. The TRT comprises a barrel containing 52 000 axial straws and two end-cap parts with 320 000 radial straws. The total of 420 000 electronic channels (two channels per barrel straw) allows continuous tracking with many projective measurements (more than 30 straw hits per track). The assembly of the barrel modules in the US has recently been completed, while the end-cap wheel construction in Russia has reached the 50% mark. After testing at the production sites and shipment to CERN, all modules and wheels undergo a series of quality and conformity measurements. These acceptance tests survey dimensions, wire tension, gas-tightness, high-voltage stability and gas-gain uniformity along each individual straw. This paper gives details on the acceptance criteria and measurement methods. An overview of the most important results obtained to-date is also given

Architecture of the upgraded BCM1F backend electronics for Beam Conditions and Luminosity measurement

The Beam Radiation Instrumentation and Luminosity Project of the CMS experiment consists of several beam monitoring systems and luminometers. The upgraded Fast Beam Conditions Monitor is based on 24 single crystal diamond sensors with a two-pad metallization and a custom designed readout. Signals for real time monitoring are transmitted to the counting room, where they are received and processed by new back-end electronics designed to measure count rates on LHC collision, beam induced background and activation products to be used to determine the luminosity and the machine induced background. The system architecture and the signal processing algorithms will be presented.